1. Field of the Invention
This invention is related in general to the field of equipment automated control and, in particular, to a system for determining the position and orientation of various components of a work machine operating on the grounds of a surface mine.
2. Description of the Related Art
Surface mines utilize a variety of work machines for excavating and transporting ore, grading and stabilizing roadways and slopes in the mine pit, and providing all support functions necessary to the operation of a mine. Most work machines, such as excavators, shovels, backhoes and the like, are human-operated, mobile pieces of equipment constantly being moved around on the surface of the mine. Skilled operators ensure that each work machine is positioned in the right place and optimally oriented to perform its intended function. For example, an excavator operator will ensure that the undercarriage of the machine is sufficiently close to the minable seam and that its boom is oriented so as to permit the bucket of the machine to reach and extract a full load of ore.
In order to improve safety and efficiency, much effort is currently under way to develop automated systems for controlling the operation of work machines in surface-mine and other environments. The ability to determine the exact position of critical components of a working machine, such as the bucket of an excavator, is a very important feature of any such effort to automate certain aspects of a mining operation. Accordingly, various positioning systems have been developed in this and related arts based on the properties of various triangulation tools such as lasers, radio, microwave, radar, and the Global Position System (GPS).
For example, in U.S. Pat. No. 5,438,771, Sahm et al. describe a system for determining the location and orientation of a work machine having a fixed undercarriage supporting a car body rotatably connected to it. The system utilizes a GPS unit placed on the car body at a place removed from its axis of rotation. By collecting at least three coordinate positions of the GPS antenna as the car body rotates over its stationary undercarriage, the plane corresponding to the orientation of the machine and the position of the axis of rotation can be calculated. Based on these data, the current position of the GPS antenna, and the geometry of the machine, the position and orientation of every critical component of the machine can be determined and used for controlling its operation.
Because of the requirement that at least three positions of the GPS antenna be recorded along an arc of rotation, the system disclosed in the '771 patent is only applicable to work machines that include a rotating body over a transport undercarriage. In addition, the system requires that the undercarriage be kept stationary during measurements and that at least three data points be collected before the plane of orientation can be determined every time the work machine is moved to a new work site. Therefore, this method and apparatus are not suitable for continuous tracking of the position of mine vehicles or for controlling equipment lacking a rotating body. The present invention provides a procedure and apparatus that overcome these deficiencies.